Diffuse shoulder pain and shoulder joint mobility disorder are the main clinical manifestations of a frozen shoulder. It often occurs on the shoulder of middle-aged and older adults. The lesion involves the shoulder, joint bursae, and other soft tissues. The incidence of frozen shoulder is 2%-5%, but its pathogenesis is unknown, and there are many limitations and poor curative effects in current treatment methods. Therefore, further understanding its pathogenesis and exploring new therapies to improve the quality of life of patients with frozen shoulders is of great significance. Animal and clinical trials have demonstrated that low-intensity pulsed ultrasound (LIPUS) can accelerate fracture healing and promote the repair of other connective tissue injuries, such as muscles, tendons, cartilage, ligaments, etc. So far, no reports have been found about the effect of LIPUS on frozen shoulder animal models. Objective To investigate the effect and mechanism of LIPUS on frozen shoulder model rabbits.

Sixty female New Zealand rabbits were randomly divided into a control group, a model group, and a LIPUS treatment group. After the frozen shoulder model was made by the method of continuous strain and ice compress, the pathological changes of the tissues around the affected shoulder were observed, and the contents of transforming growth factor-β1 (TGF-β1), prostaglandin-E2 (PGE-2) and hydroxyproline (HYP) in serum were detected.

With a single variance analysis of multiple data groups, it was found that the contents of TGF-β1, PGE-2, and HYP in the LIPUS treatment group were significantly decreased compared with the model group. In contrast, the contents in the model group were significantly increased compared with the blank control group, with statistically significant differences (P < 0.05). The results of the pathological section showed that the degree of synovial hyperplasia and tendon fiber hyperplasia were improved in the treatment group, and the tissue repair was accelerated.

LIPUS can achieve anti-inflammatory and analgesic effects by reducing the contents of TGF-β1, PGE-2, and HYP in the frozen shoulder tissues of New Zealand rabbits, which is worth promoting in clinical use.